Suddenly reminded of this and actually its even funnier than I initially thought because Dazai and Chuuya do not fit the Idealist vs Pragamist trope... Dazai is pragmatic yes but the example given is not what pragmatism is at all
Being pragmatic is not about ethics or doing morally wrong things, its about being practical, realistic, down to earth. I'd argue both Dazai and Chuuya are pragmatic people, just in different ways.
But hmmm I wonder if there is a BSD character who is an idealist... someone who is so synonymous with the word "Ideal" that they carry around a little green notebook that has the Japanese word "理想" (ideals) written on the front cover. If someone is discussing idealism in BSD and Kunikida is not the immediate first example used I do not believe they actually read/watched BSD. (the only exception I'd make is Atsushi)
Not to say Chuuya doesn't have some traits that could be considered idealistic, but its not a core part of his character in the same way it is for Kunikida
If you want a good example of "Idealist vs Pragmatist" in BSD, take the argument between Kunikida and Dazai at the end of Dazai's Entrance Exam:
Sasaki and Rokuzo are dead, Kunikida is on the verge of a breakdown as he tries to argue there was no reason for them to die and there had to have been a way for them to live without any further suffering; Dazai tells him that that was how it had to be, Sasaki was a terrotist and she had no intentions of stopping if she lived.
Kunikida is being an idealist in this situation, especially in regards to Sasaki. He knows she was a terrorist and yet he believes that killing her wasn't the only solution to stopping her from continuing her terrorism. And he's could have very easily been right as the only reason she was a terrorist was because of how much she loved the Azure King.
Dazai is being pragmatic as he believes that Sasaki's death was the only way to stop her. Sure it is possible that she could have been able to stop if she had the right guidance from others, but that is not a guarentee. Its not worth it to to risk potentially hundreds of peoples lives just to keep one woman from dying.
We all know what type of BSD "fan" wrote this entry. I genuinely want to know what kind of mental gymnastics one has to go through to see the trope "Idealist vs Pragmatist" for a duo with Dazai and not immediately use Kunikida for idealist. Its 100% just trying to push an unnecessary shipping agenda because in literally no universe is any BSD character more of an idealist than Kunikida, let alone fucking Chuuya of all people.